Apparatus to automatically determine the angular position of unbalance in rotatable bodies



y 3, 1938. J. SWERTSEN- A 2,116,221 APPARATUS T0 AUTOMATICALLY DETERMINE THE ANGULAR POSITION OF UNBALANCE IN ROTATABLE BODIES Filed Aug. 31, 1935 INVENTOJIQ.

Patented May 3, 1938 2,115,221.

UNITED STATES PATENT oFFIcE MINE THE ANGULAR POSITION OF UN- BALANCE IN ROTAT'ABLE BODIES Jens Sivertsen, Philadelphia, Pa. Application August 31, 1935, Serial No. 38,710

'9 Claims. (01. 73-51) For high speed balancing of rotatable bodies, rent are produced by the forces arising from the such as armatures for electrical motors, crankunbalance of the body, at which position it will shafts for gasoline motors, and other rotatable always have the same polarity.) If a carrier bodies in mass production, means have been decarrying the magnets of fixed polarity is free veloped, which will give an indication of the to move angularly it will adjust itself to move amount of unbalance by the reading of an elecinto this angular position and a carrier carrying trical meter. alternating coils will act similarly. From this The devices previously used can be designated the angular direction of the unbalance can be as half-automatic, as the angular position had read, directly by a suitable scale or by other 1 to be found by tuning a dial, or by stroboscopic means. In my present device, the vibrations proor other auxiliary devices. duced by the unbalance of the body tested are A machine which automatically will also give usually sufficient to produce an alternating curthe angular position of the unbalance will inrent through the rotated magnets. crease the speed of production very much, and For the purpose of illustrating the invention,

be a true automatic balancing machine. I have shown in the accompanying drawing a This invention is not in any way concerned with typical embodiment of it, which in practice, will how the amount of unbalance is found, as this give reliable and satisfactory results. This drawinvention can be utilized together with any deing and its description in this specification are vices to determine the amount of unbalance. not to be taken, however, as limiting my inven- 2 It will however be very easily adaptable to tion to the construction shown therein. This means whereby-the amount is found automatiembodiment while the best form of my device cally by reading of a current through an elecof which I am at present aware is typical only, trical meter, as commonly known. and the various instrumentalities of which my The device comprises a rotor carrying magnets, invention consists can be variously arranged and which is positively driven, and is secured to reorganized, and the invention is not limited to the volve with the body, the direction of the angular pr n m n nd or nization as set unbalance of which is to be determined, so that forth. a r i the two will rotate together. It comprises also Fig. 1 is an elevation partly in section of my a carrier free to move angularly with reference device, Fig. 2 is an end elevation also partly in to the rotor and also carrying magnets. This section and-partly schematic. l is the body to 3 carrier is preferably a rider rotatable with an be balanced supported by a bearing 2, which is axis that coincides substantially with the axis part of a cradle 3, or any other arrangement of revolution of the rotor. One of these two allowing the unbalanced forces to excite an elece1ements-rotor and carrier--carries magnets tric pick up unit in such a manner that an alterthat are of a fixed polarity and the other of them nating electric voltage, synchronous with the vi- 35 carries magnets of alternating polarity, the mag bration of the body to be balanced will result from nets of alternating polarity are excited by the this excitation-as commonly known in the art. alternating current caused by the vibrations aris- 4 is a coupling preferably a universal joint whereing from the rotation of. the body, the angular by body I is rotated by the shaft 5 which in turn position of unbalance of which was to be deteris rotated by a pulley 6, driven by a belt I, from 40 mined. The word magne is used in its broad a motor or in any other way. 8 is a graduated sense and includes permanent magnets and drum which by a set-screw, pin, or in any other solenoids excited by alternating as well as direct Way can be fastened to the shaft 5. 9 and ID are currents. The magnets of the carrier and the two brackets rigidly fastened to a frame H. In

5 rotor are arranged so that those of one of these bracket H] is drilled a hole wherein the sleeveelements is free to pass the poles of the other. bearing I2 is inserted to support the shaft 5. In Where the magnets excited by the alternating bracket 9 is in the same manner inserted the currents are placed on a rotor and the latter is sleeve l3, which also acts as a sleeve-bearing for. rotated synchronously with the alternations of shaft 5. The outside surface of the upper portion the current, each pole alternates in its polarity of the bracket 9 is concentric with the hole in 50 and each pole is most strongly magnetized when which the sleeve [3 is inserted and is turned in at one angular position, which is decided by the a lathe to give a smooth circular surface [4. angular position of the unbalance. A like con- The two ball-bearings l6 and ll are supported dition occurs where the alternating coils are on this surface with their inside rings l8 andl9.

placed on the carrier if the alternations of cur- The outside rings 20-4! of the ball-bearings 55 carry the circular carrier 22. The outside of this carrier may carry also the scale which may be graduated at 51 like the drum 8.

A stack of field laminations 24 is fastened to the carrier 22' by the screw bolts 23.

The insulating ring 25 carries two slip rings 26 and 21 that are insulated from each other. These three rings form a solid structure and are rigidly fixed to the carrier 22.

The laminations 24 carry the two field coils 28 and 29. These coils may be regarded as one coil as they are connected directly in series. The terminals 30 and 3| of this coil are connected to the slip-rings 26-21 respectively and the latter are in contact with the brushes 32 and 33 respectively that are connected electrically with a source of direct current having the terminals 34 and 35. If 34 is the plus side a current will pass from 34 to brush 32, slip-ring 26, coil terminal 30 to coil 28-29; from coil to terminal 3|, slip-ring 21, brush 33 and to the other terminal 35, thus completing the circuit. The carrier 22 with the laminations, coils, and slip-rings is a rider riding freely on an axis that is coaxial with the axis of shaft 5. On shaft 5 are rigidly fixed rotor laminations 36, and the insulating ring 31. To the rotor laminations are fixed the coils 54-55 connected in series. Their terminals |556 are connected to the slip-rings 38-39 which are insulated from each other and are fastened to the insulating ring 31. When shaft 5 is rotated by pulley 6 the body to be balanced, the armature 36 with coils, slip-rings 38 and 39, the insulating ring 31, will all rotate with the shaft. The carrier 22 and the parts carried by it, are free to seek their own angular position around the same axis and do not have to rotate with shaft 5.

When the body to be balanced is rotating it will by its unbalanced forces create an alternating electric current designated diagrammatically through some kind of a pick up arrangement designated diagrammatically by coil 40, if the cradle or support is so arranged. This pick up may be electromagnetically or electrostatically arranged, or be arranged in such a manner that the properties of piezo electric crystals are utilized-as commonly known in the art. The phase angle of this current relative to shaft 5 and drum 8 is decided by the angular position of the unbalance, as well known in the art. The terminals of the pick up arrangement are the insulated points 4| and 42. The insulated wires 43 and 44 conduct this generated pick up current tothe input terminals 45 and 46 of a vacuum tube amplifier 47. From the output terminals 48 and 49 of this amplifier the amplified current, containing much more energy than the input, passes through insulated wires 50 and 5| and is conducted through the brushes 52 and 53, which are contacting the slip-rings 3B and 39 to the coils.

When an unbalance is present in the body to be balanced I will therefore get an amplified alternating current and voltage from the output terminals of the amplifier 41 from 48 through 50 to brush 52, slip-ring 3B armature coil 54-55, slip-. ring 39, brush 53, wire 5| to 49, thus completing the circuit. The phase angle of this current is dependent on the angular position of the unbalance.

For a further understanding of the workings of the arrangement I will turn to the schematic end view Figure 2.

The same designations as in Figure l are used.

Figure 2 shows the armature lamination 36 with its coil 54-55 and terminals l5 and 56.

These terminals are connected to slip-rings 38 and 39 as previously outlined and shown in Figure 1.

The outside stack of laminations 24, with its coil 28--29 has the terminals 30 and 3| that are, as explained connected to slip-rings 25 and 21.

The coil 28-29 which is supplied with direct current through its terminals 39 and 3|, will give the outside stack of laminations a distinct magnetic polarity. I assume this polarity to be a north pole at the side designated N and a south pole at the side designated S.

The inside stack of laminations 36 will not have a certain polarity as the coil is supplied with alternating current. It will therefore change its polarity once every cycle. Once every cycle it will have a north pole at A and once at B and once every cycle it will have a south pole at B and once at A. The strength of these poles will also continually vary with the supplied alternating current.

The armature 36 with its coil 54-55 is at the same time rotating synchronously with the rotating body.

If I assume that at an angle a from the vertical plane I get the maximum strength of a south pole at A, and at B a north pole, I will half a rotation after, when E is near C and A near D, have a south pole in the B end and a north pole in the A end.

This means that the maximum strength of the north pole will always occur in the same relative position to the vertical plane, and so will the south pole.

As the magnetic field lines always strive to shorten themselves as much as possible, and as the coil 28--29 with laminations 24 is free to move around the ball-bearings I6 and I1, Figure l and thus take any angular position, the coil with laminations 24 will turn to take the angular position that will give it in average the shortest field lines.

The pole N of 24 will therefore move over to C and S to D and take the angular position a thus indicating the position where the amplified unbalance current is the strongest, thus enabling the operator to read the angular position of the unbalance on the graduations 5'! by reference to the pointer 58. By turning the pulley 6 after the motor has been stopped, until the pointer 59 points at the same number on the drum 8--as the pointer 58 points at, on the scale 51, the operator has found the unbalance to be at that angle, relative to his selected zero point.

If in addition, the arrangement is provided with a sensitive meter 60, the operator will when the machine is running also have means to read' directly the voltage created by the unbalanced forces and thus simultaneously have an indication of the amount of unbalance.

The amplifier should also have a phase distor-' tion not changing with the input signal. Re-

sistanceor transformer-coupling between the Choke coupling lamination as shown in Figures 1 and 2 can also be replaced by a permanent magnet instead of the coil with lamination and slip-rings.

In the outlined arrangement the armature 36 and the body to be balanced l are mechanically connected to give synchronous rotation. I do not, however, limit myself to these means of connecting it.

It should also be possible to do away with the vacuum tube amplifier for special applications where the electric energy resulting from the unbalanced forces is big enough and the outlined electromagnetic arrangement can be built light enough to indicate for a small energy.

It is also possible to do away with the steel laminations in the magnetic paths in applications where the bearing friction can be made small enough or where the applied currents are strong enough and generally I do not limit myself to the form of device set forth which is the best formof which I am at present aware, as many changes may be made without departing from my invention.

Having thus described my invention, what I claim as new, and what I wish to secure by Letters Patent is:-

1. An electromagnetic device to automatically locate the angular position of unbalance in rotatable bodies comprising a coil rotating synchronously with the body to be balanced and supplied with alternating current from the body to be balanced, means activated by the vibrations of said body for supplying said alternating current, an outside permanent magnetic ring, supported concentric with the rotating coil but free to seek its own angular position.

2. An electromagnetic device to automatically locate the angular position of unbalance in rotatable bodies consisting of a rotor carrying a coil rotating synchronously with the body to be balanced, supplied with alternating current originating from body to be balanced, electric means operated by the vibration of said body supplying said alternating current, a carrier, mounted coaxially with said rotor and carrying a second coil, supplied with direct current, said carrier being free to seek its own angular position.

3. An apparatus for determining the angular position of the unbalance in a rotatable body, comprising a positively driven rotor, and a carrier, free to turn on the same axis as the rotor, one of these two elements carrying magnets of fixed polarity and the other of said elements carrying coils of alternating polarity, the poles of said magnets of fixed polarity being revolv able to be opposite the positions of greatest strength of the coils of alternating polarity, means for rotating the said body synchronously with said rotor, and means for producing in the coils of alternating polarity, alternating currents generated by the unbalanced forces in said body, synchronous with the revolutions of the rotor and said body, said carrier being free to seek its own angular position.

4. An apparatus to determine the angular position of unbalance in rotatable bodies, consisting of means consisting of a rotor rotated synchronously with the body to be balanced, a second means consisting of a rider rotatable coaxially with said rotor and, free to seek any angular position relative to a predetermined zero point, one of said means having a fixed polarity and a device for supplying the other of said means with an alternating current originating from the unbalanced forces in the body to be balanced.

5. An electromagnetic device to automatically locate the position of unbalance in rotatable bodies, comprising two instrumentalities, namely, a rotor and a carrier, each instrumentality carrying coils and being mounted coaxially with the other, the rotor being rotated synchronously with the body to be balanced and the carrier being free to seek its own angular position, a pick up mechanism whereby the forces due to unbalance are changed into an alternating voltage, and electrical conducting means between the pick up mechanism and one of said instrumentalities.

6. An electromagnetic device to locate automatically the angular position of unbalance in a rotatable body, consisting of two coaxially rotatable elements, each carrying coils, one of said elements being rotated synchronously with said body, and the other of them being free to seek its own angular position, the coils of one element being of constant polarity, and means for supplying the coilsof the other with alternating current originating from the unbalance.

'7. An electro-magnetic device to automatically locate the angular position of unbalance in rotatable bodies, comprising electrical pick up means excited by the vibrations of said body to be balanced, a coil rotating synchronously with said body to be balanced, said coil supplied with alternating current from said pick up means, an exterior carrier carrying a coil, said coil supplied with direct current, said carrier supported coaxially with said rotating coil, but free to seek its own angular position.

8. An apparatus for determining the angular position of unbalance in a rotatable body, comprising a rotor and a carrier, said rotor rotated synchronously with said body to be balanced, said rotor having a coil and means for producing in said coil alternating current generated by the unbalanced forces in said body to be balanced, said carrier having a magnet, said carrier supported coaxially with said rotor, but free to seek its own angular position.

9. An apparatus to determine the angular position of unbalance in a rotatable body, comprising electrical pick up means generating alternating voltage by the vibrations due to unbalance in said body, a rotor and a magnet, said rotor having a coil, said coil supplied with alternating current originating in said pick up means, means to support said magnet coaxially with said rotor, but free to seek its own angular position.

JENS SIVERTSEN. 

